A dual-pinion or dual-stem door lock has a pair of normally vertically offset pinions in which can be seated respective stems for respective door handles or actuators. In a standard installation one of the stems, the one that carries the inside door handle, is coupled to the bolt operated by the lock so that it can always retract this bolt. The other stem carries the outside door handle and can be blocked or disconnected from the door-bolt so that the door can be locked. Thus a door equipped with such a latch can always be opened from inside, but can be locked from the outside. Typically a key-operated mechanism provided underneath the outside door stem serves to couple and decouple the outside handle from the operating mechanism of the lock.
Thus with such a lock one of the door handles or knobs is typically mounted at a lower level than the handle on the opposite face of the door. This not only looks odd when the door is seen from the edge, but is counter to standard good design practices which mandate a regulation height for door handles. What is more if the lock is installed such that the outside handle is the lower handle, there is frequently insufficient clearance underneath the outside handle to get to the key, making its use difficult.
French patent 2,239,894 describes a handle-actuating assembly that can be installed on a door to displace the door handle or knob horizontally away from the edge of the door. Such an assembly is used on a conventional latch and constitutes an ugly attachment to the otherwise neat lock. It adds no extra functionality to a dual-pinion door lock.